E – 1651 Overcurrent Protection Fundamentals

Relay protection against high current was the earliest relay protection mechanism to develop. From this basic method, the graded overcurrent relay protection system, a discriminative short circuit protection, has been formulated. This should not be mixed with ‘overload’ relay protection, which typically utilizes relays that function in a time related in some degree to the thermal capacity of the equipment to be protected. On the contrary, overcurrent relay protection is completely directed to the clearance of short circuits, even though with the settings typically assumed some measure of overload relay protection may be obtained.

This course is suitable for engineers with a desire to understand overcurrent protection fundamentals. Course covers co-ordination technique, rules for time/current grading, IDMT overcurrent protection curves, grading relay-relay, fuse-fuse and fuse-relay, protection relay connections, directional protection and ground fault protection.